FIG. 1 of this patent document shows a representative figure for U.S. Pat. No. 5,950,945 to Schaller (which is incorporated herein by reference), wherein a replaceable tooth PA1 has a leading face PA2, a trailing face PA3, a radially outer face PA4 and a radially inner face PA5. The leading face PA2 has cutting portion PA6 on it. The trailing face PA3 is disposed along a first plane PA7 and a radially inner face PA5 is disposed in a second plane PA8. The replaceable tooth PA1 is held in place with a threaded fastener PA10 disposed along a longitudinal axis PA11 in a tooth holder PA9. The axis PA11 is disposed at an angle of PAa with respect to the plane PA8 coincident with the radially inner face PA5.
Still referring to FIG. 1, the longitudinal axis PA11 intersects the plane PA8 at a point (PA12) in front of the leading edge PA2 of the tooth PA1 as it rotates about a rotational axis (not shown). Due to that just described structural relationship, when the threaded fastener PA10 of the Schaller device is tightened, the trailing face PA3 of the Schaller cutting tooth PA1, as shown herein in FIG. 1, is pulled against the leading face PA14 of the tooth holder PA12. However, also as a result of that tightening procedure, the bottom or radially inner face PA5 of the Schaller tooth PA1 has forces on it in use tending to cause it to be pulled away from the mating surface PA15 of the tooth holder PA12. So, the tightness being increased on only one of the abutting surfaces PA3/PA14, instead of on both abutting surfaces, PA3/PA14 and PA5/PA15, makes the tooth PA1 less stable than it could otherwise be. This problem will be explained in more detail in the following paragraph and in relation to FIGS. 1A and 1B.
FIGS. 1A and 1B show the forces on the Schaller prior art tooth PA1 of FIG. 1 wherein, as shown in FIG. 1A, a vector PAV extending generally from the leading face PA2 towards the trailing face PA3 along the longitudinal center PA11 can be broken into a component PAVC1 perpendicular to and directed towards the trailing face PA3 and a corresponding component PAVC2 parallel to the trailing face PA3 that is directed towards the radially inner face PA5; and FIG. 1B shows a component PAVC3 perpendicular to and directed away from (not towards as in the present invention) the radial inner face PA5 and a corresponding component PAVC4 parallel to the inner face PAVC4 that is directed towards the trailing face PA3.
Accordingly, there is a need for a cutting tooth and holder wherein a tightening of a cutting tooth fastener will pull both a rear or trailing face PA3 and a bottom or radially inner face PA5 of the tooth against abutting surfaces of a tooth holder, whereby both the rear and bottom surfaces of the cutting tooth are in a tight abutting relationship with the abutting surfaces of the tooth holder, as result of a positive force vector being induced against both of those surfaces.
Elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions and/or relative positioning of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present invention. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present invention. Certain actions and/or steps may be described or depicted in a particular order of occurrence while those skilled in the art will understand that such specificity with respect to sequence is not actually required. The terms and expressions used herein have the ordinary technical meaning as is accorded to such terms and expressions by persons skilled in the technical field as set forth above except where different specific meanings have otherwise been set forth herein.